Combination of chemical oxidation-membrane filtration processes for the elimination of phenyl-ureas in water matrices

摘要

BACKGROUND: Phenyl-urea herbicides are found in surface waters and wastewaters as a consequence of their extensive use inagriculture. Due to their pollutant power, the removal of phenyl-ureas is a priority objective in water treatment technologies. RESULTS: Four selected phenyl-ureas herbicides (linuron,diuron,chlortoluron and isoproturon), dissolved in two water matrices(a groundwater and and a reservoir water), were subjected to sequential combinations of chemical treatments and membranefiltration processes. Two specific sequences were conducted: first, a chemical oxidation stage (where UV radiation, ozone andozone plus hydrogen peroxide were used) followed by a nanofiltration process; and second, a membrane filtration stage (usingUF and NF membranes) followed by an ozonation stage. Values for the herbicide removals in the oxidation stages and for therejection coefficients in the filtration stages are provided, and the partial contribution of the different stages is established foreach combined treatment. CONCLUSIONS: High removals (over 80%) were reached for phenyl-ureas elimination by most of the combined processes tested.In the combined chemical oxidationanofiltration processes, the most effective was an ozonation pretreatment ([0310 = 1.5mg L-1)) followed by a NF step. In the opposite sequence filtration/chemical oxidation, the most effective was a NF pretreatmentfollowed by the ozonation ([O_3]_0=2 mg L~(-1)).